ALSA: ac97 - Add patch entry for Conexant CX20468-31 chip

Added the patch entry for Conexant CX20468-31 chip (4358:5430).

Reference: Novell bnc#471265
	https://bugzilla.novell.com/show_bug.cgi?id=471265



Signed-off-by: Takashi Iwai <tiwai@suse.de>